In the field of liquid crystal display technology, a liquid crystal display panel mainly includes a color filter substrate and an array substrate which are arranged in a cell aligning manner. The color filter substrate is mainly provided with a color filter (namely a color resin layer) thereon, the array substrate is mainly provided with a pixel array thereon, each pixel unit in the pixel array is correspondingly provided with a thin film transistor (TFT) functioning as a switch, and the drain of the TFT is connected with a pixel electrode in the pixel unit to provide a gray-scale voltage for the pixel electrode so as to realize image display.
In recent years, with continual requirements of people for display panels with high aperture ratio and high brightness, a technology of directly forming a color filter on array (COA) is developed, and the COA technology can improve the aperture ratio, reduce the cost and improve the display quality of a product by reducing the error between the array substrate and the color filter substrate during cell forming.
A color filter on array substrate (namely COA substrate) formed through the COA technology in the prior art includes pixel units distributed in an array manner, wherein each pixel unit includes a TFT, a color resin layer and a pixel electrode, and the pixel electrode is electrically connected with the drain electrode of the TFT through a via hole on the color resin layer. When the via hole on the color resin layer is made in the prior art, it is obtained by directly exposing and developing the color resin layer using a mask. However, the resolution of the color resin layer is generally low, and the minimum critical dimension (CD) or hole size (Hole Size) realized after the color resin layer is exposed and developed is relatively large, so that the aperture ratio of pixels is affected.